FEH catchment descriptors

Introduction

FEH (Flood Estimation Handbook) catchment descriptors provide the catchment characteristics and rainfall data to support the methods outlined in the Flood Estimation Handbook to estimate river flows.  Catchment descriptors were originally published in 1999 alongside FEH and have been updated and maintained by UKCEH since.  There are two sources of catchment descriptors:

1. National River Flow Archive (NRFA) Peak Flow Database - FEH Catchment Descriptors are provided by UKCEH for all Peak Flow river gauges in the UK

2. FEH Web Service - A paid for service by UKCEH which provides catchment descriptors for all ungauged river catchments in the UK with an area greater than 0.5km²

Software Compatibility

Flood Modeller 7.4.0

Flood Modeller v7.4.0 supports the additional FEH catchment descriptors introduced in the 2025 update (Catchment Descriptor dataset v5.1.0). New descriptors available in Hydrology+ include:

• SAAR9120 (1991–2020 rainfall update),

• FARL2015,

• URBEXT2015,

• BFIHOST19SCALED.

The catchment descriptor dataset version is now stored with the catchment descriptor record in the Hydrology+ database and is shown in the descriptor metadata.

Further details on the introduction of the Catchment Descriptors can be found on the CEH website: The FEH 2025 Statistical Updates | UK Centre for Ecology & Hydrology.

If you create a calculation point at an NRFA gauge site, ensure your connected Peak Flow Dataset is v14 (NRFAPeakFlow_v14-0-1) or later to access the newer descriptors at gauge sites. Earlier Peak Flow Dataset versions do not include the 2025 descriptor variables.

Flood Modeller Versions Prior to 7.4.0

Flood Modeller versions predating 7.4.0 are compatible with v13 and earlier versions of the NRFA/UKCEH Peak Flow database.  With v13, there are two sub-versions, 13.02 which is in the older format and 13.03 which is in a new format.  As well as the usual inclusion of new years of data, the following format changes have been made in v13:

1. All files name named with gauge name as well as number, e.g. "002001.xml" becomes "002001-helmsdale-at-kilphedir.xml"

2. New "IHDTMEASTING and IHDTMWESTING" values has been added to the XML scheme on row 16/17

3. The AMAX (.am) and POT (.pt) files now have data in yyyy-mm-dd hh:mm:ss format rather than dd mmm yyyy

Use of Catchment Descriptors in Hydrology+

Hydrology+ has been enhanced to ensure it can seamlessly utilise data from either format of the Peak Flow database.

Hydrology+ supports access to catchment descriptors from both NRFA and the FEH Web Service as described in the FEH Catchments article. Viewing catchment descriptor locations and extents is described in FEH catchments view. 

Imported FEH catchment descriptors provide parameters integral for UK hydrological (ReFH2/WINFAP) analysis. 

From this window, the following options are available:

To make use of catchment descriptors in analysis, a calculation point needs to be created.